Merge pull request matplotlib#31661 from tacaswell/bld/static_analysis

BLD: add more static analysis

Author: QuLogic

.clang-tidy

@@ -0,0 +1,36 @@
+---
+# clang-tidy configuration for matplotlib's src/ directory.
+#
+# Philosophy: enable checks that find real bugs (memory safety, undefined
+# behaviour, security) and suppress checks that are high-noise style rules
+# inappropriate for a C/C++ codebase that interfaces heavily with C APIs
+# (CPython, FreeType, libagg) via pybind11.
+#
+# Run with:
+#   clang-tidy -p <build_dir> --config-file=src/.clang-tidy <file>
+
+Checks: >
+  bugprone-*,
+  clang-analyzer-*,
+  objc-*,
+  performance-move-const-arg,
+  performance-move-constructor-init,
+  performance-no-automatic-move,
+  portability-*,
+  -bugprone-assignment-in-if-condition,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-implicit-widening-of-multiplication-result,
+  -bugprone-macro-parentheses,
+  -bugprone-narrowing-conversions,
+  -bugprone-reserved-identifier,
+  -bugprone-throwing-static-initialization,
+  -clang-analyzer-optin.cplusplus.UninitializedObject,
+  -clang-analyzer-optin.performance.Padding,
+
+# Only report findings in matplotlib's own src/ headers, not in pybind11,
+# Python.h, agg, or other vendored includes.
+HeaderFilterRegex: '.*/matplotlib/src/.*'
+
+WarningsAsErrors: ''
+
+CheckOptions: []

.github/dependabot.yml

@@ -5,6 +5,8 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       actions:
         patterns:
@@ -13,9 +15,13 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     exclude-paths:
       - "ci/minver-requirements.txt"
   - package-ecosystem: "pre-commit"
     directory: "/"
     schedule:
       interval: "monthly"
+    cooldown:
+      default-days: 7

.github/workflows/autoclose_schedule.yml

@@ -23,15 +23,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
       - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
         with:
           python-version: '3.13'
       - name: Install PyGithub
         run: pip install -Uq PyGithub
 
-      - name: Checkout repository
-        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
-
       - name: Close PRs labeled more than 14 days ago
         run: |
           python tools/autoclose_prs.py

.github/workflows/linting.yml

@@ -84,6 +84,37 @@ jobs:
               -tee -reporter=github-check -filter-mode nofilter
 
 
+  clang-tidy:
+    name: clang-tidy (macOS / Objective-C)
+    runs-on: macos-latest   # run on macOS so we can lint the objectiveC file
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Set up Python 3
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
+        with:
+          python-version: '3.14'
+
+      - name: Install OS dependencies
+        run: brew install llvm
+
+      - name: Install build dependencies
+        run: pip3 install meson ninja pybind11 setuptools-scm
+
+      - name: Run clang-tidy
+        run: |
+          set -o pipefail
+          LLVM_PREFIX=$(brew --prefix llvm)
+          export CC=$LLVM_PREFIX/bin/clang
+          export CXX=$LLVM_PREFIX/bin/clang++
+          export OBJC=$LLVM_PREFIX/bin/clang
+          export PATH=$LLVM_PREFIX/bin:$PATH
+          python tools/run_clang_tidy.py
+
   eslint:
     name: eslint
     runs-on: ubuntu-latest

.github/workflows/zizmor.yml

@@ -0,0 +1,30 @@
+---
+name: zizmor
+
+on:
+  push:
+    branches: [main, v*.x]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: '45 19 * * 1'
+
+permissions: {}
+
+jobs:
+  zizmor:
+    name: zizmor
+    if: github.repository == 'matplotlib/matplotlib'
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Run zizmor
+        uses: zizmorcore/zizmor-action@b572f7b1a1c2d41efaab43d504f68d215c3cd727  # v0.5.4

.github/zizmor.yml

@@ -0,0 +1,19 @@
+---
+rules:
+  dangerous-triggers:
+    ignore:
+      # These workflows use pull_request_target solely to obtain write access
+      # for API operations (labeling, commenting) on fork PRs. None of them
+      # check out or execute any PR-supplied code.
+      - autoclose_comment.yml:11
+      - conflictcheck.yml:3
+      - labeler.yml:3
+      - pr_welcome.yml:4
+  cache-poisoning:
+    ignore:
+      # cygwin.yml is a test-only workflow; no artifacts are published.
+      # This is triggering a low-confidence flag that the  workflow_dispatch:
+      # trigger may imply artifact publishing
+      - cygwin.yml:144:9
+      - cygwin.yml:151:9
+      - cygwin.yml:158:9

.pre-commit-config.yaml

@@ -77,6 +77,22 @@ repos:
     hooks:
       - id: yamllint
         args: ["--strict", "--config-file=.yamllint.yml"]
+  - repo: https://github.com/shellcheck-py/shellcheck-py
+    rev: 745eface02aef23e168a8afb6b5737818efbea95  # frozen: v0.11.0.1
+    hooks:
+      - id: shellcheck
+  - repo: https://github.com/zizmorcore/zizmor-pre-commit
+    rev: a4727cbbcd26d7098e96b9cb738169b59711ae51  # frozen: v1.24.1
+    hooks:
+      - id: zizmor
+  - repo: https://github.com/simple-icons/svglint
+    rev: 8402586b94f073686e46707a163082e270ee5768  # frozen: v4.2.1
+    hooks:
+      - id: svglint
+        # Override the top-level exclude so that mpl-data/images/ toolbar
+        # icons are also linted.  Exemptions for the intentional interactive
+        # SVG examples are handled in .svglintrc.mjs.
+        exclude: '^$'
   - repo: https://github.com/python-jsonschema/check-jsonschema
     rev: f805888065fdb6162e1f800e50bb9460cbd223d6  # frozen: 0.37.2
     hooks:

.svglintrc.mjs

@@ -0,0 +1,56 @@
+/** @type {import('svglint').Config} */
+const config = {
+    rules: {
+        // Ensure all SVGs are valid XML.
+        valid: true,
+
+        // Block elements that can execute code or embed arbitrary content.
+        // <script> can run arbitrary JavaScript; <foreignObject> and <iframe>
+        // can embed arbitrary HTML.  Unlike event-handler attributes (which
+        // are a legitimate tool for matplotlib's interactive SVG examples),
+        // there is no use case in this repository for these elements outside
+        // of a <script> already paired with its own exemption.
+        elm: {
+            "script": false,
+            "foreignObject": false,
+            "iframe": false,
+        },
+
+        custom: [
+            // Block external URL references in href / xlink:href.
+            // Internal fragment references (#id), data: URIs, and relative
+            // paths are all fine.  http/https/ftp and protocol-relative URLs
+            // are blocked because they cause the SVG renderer to make an
+            // outbound network request, leaking the viewer's IP and UA to an
+            // attacker-controlled server.
+            (reporter, $, _ast) => {
+                reporter.name = "no-external-references";
+                const externalPattern = /^(https?:|ftp:|\/\/)/i;
+                $("[href], [xlink\\:href]").each((_i, el) => {
+                    if (!el.attribs) { return; }
+                    const href =
+                        el.attribs["href"] ?? el.attribs["xlink:href"];
+                    if (href && externalPattern.test(href)) {
+                        reporter.error(
+                            `Found external reference '${href}' on <${el.name}>. ` +
+                            "External URL references in SVGs cause the renderer " +
+                            "to make an outbound request, leaking viewer IP/UA."
+                        );
+                    }
+                });
+            },
+        ],
+    },
+
+    // These four files are intentional interactive SVG examples that
+    // demonstrate matplotlib's SVG interactivity features.  They contain
+    // embedded ECMAScript by design and are exempted from the <script> rule.
+    ignore: [
+        "doc/_static/svg_histogram.svg",
+        "doc/_static/svg_tooltip.svg",
+        "galleries/examples/user_interfaces/images/svg_histogram.svg",
+        "galleries/examples/user_interfaces/images/svg_tooltip.svg",
+    ],
+};
+
+export default config;

doc/devel/coding_guide.rst

@@ -131,6 +131,44 @@ C/C++ extensions
   implement new features only if the required changes cannot be made elsewhere
   in the codebase.  In particular, avoid making style fixes to it.
 
+.. _clang-tidy:
+
+Static analysis with clang-tidy
+-------------------------------
+
+Matplotlib's C/C++ sources in :file:`src/` are checked with
+`clang-tidy <https://clang.llvm.org/extra/clang-tidy/>`__ in CI (see
+:file:`.github/workflows/linting.yml`).  The check
+configuration lives in :file:`.clang-tidy`.
+
+The logic lives in :file:`tools/run_clang_tidy.py`.  It requires
+``clang-tidy`` on ``PATH`` and ``meson`` and ``pybind11`` installed::
+
+    pip install meson pybind11 setuptools-scm
+
+On macOS, ``clang-tidy`` is not on ``PATH`` after a Homebrew install::
+
+    brew install llvm
+    export PATH=$(brew --prefix llvm)/bin:$PATH
+
+The script uses a dedicated ``build/clang-tidy/`` directory (created
+automatically on first run) and delegates to meson's built-in
+``clang-tidy`` target. To run locally:
+
+.. code-block:: bash
+
+   python tools/run_clang_tidy.py
+
+
+To suppress false-positives use narrow checks and a comment:
+
+.. code-block:: c++
+
+   *indices++ = value;  // NOLINT(clang-analyzer-security.ArrayBound): loop
+   // iterates exactly N times; the analyzer cannot prove this from the macro.
+
+
+
 .. _keyword-argument-processing:
 
 Keyword argument processing